The main objectives of the proposed research program are the following; 1) to find out whether the cerebellar cortex of the anterior lobe represents a sidepath to the vestibulospinal reflex arc, which is activated during the positional reflexes evoked by natural stimulation of mascular labyrinthine receptors; 2) to study whether the Purkinje neurons responding to the macular input contribute to the cerebellar corticovestibular projection, thus being able to modify the reflex response of vestibulospinal neurons to macular labyrinthine stimulation; 3) to find out whether the same Purkinje neurons may continuously integrate not only the input originating from macular receptors, but also the somatosensory input originating from neck receptors, which signals the actual displacement of the head occurring during the positional reflexes; 4) to identify the independent channels through which the macular and the cervical input of one side may produce mossy fiber and/or climbing fiber responses of Purkinje neurons located in the ipsilateral or the contralateral vermis of the anterior lobe; 5) to find out whether the confliding postural responses reflexly driven by macular and cervical receptors may be resolved at the level of the cerebellar cortex of the anterior lobe; 6) to evaluate the contribution of different size motoneurons in activating the Renshaw inhibitory circuit; 7) to investigate the role that well identified vestibulooculomotor neurons exert in the saccadic movements occurring in decerebrate cats following depletion of monoamines in the brain stem produced by reserpine.